Keywords: stress distribution, woven fabric, compressive strength, drilling parameters, carbide drill.

Composite materials are increasingly used in high performance applications such as space vehicles, aircraft, defense equipment and sports goods because of superior strength to weight and stiffness to weight ratio. In the present scenario the usage of reinforced plastics for wider application is increasing. The usage of composite materials for a specified application relies on the mechanical properties. Composite materials contain holes of various sizes for joining. Among various machining process conventional drilling is probably the most frequently used hole making process in the composites industry. The holes in composite laminates produce stress concentration. Stress concentrations produced in the laminate around hole will reduce the mechanical properties and ultimately reduce the load carrying capacity. Stress concentration is the function of laminate anisotropy, hole geometry and the drilling parameters. High stress concentration produces complex damage zones around the hole. The prediction of reduction of mechanical properties caused by holes is important for composite designers. Thus, it is of significant industrial importance to predict the effect of drilling on the mechanical properties of composite laminates. A viable and accurate method for the prediction of mechanical properties of notched composite laminates does not currently exist.

This work is focused on arriving at the basic mechanical properties of GFRP composites with hole and to evaluate the stress distribution around hole after drilling. The influence of drilling parameters on the compressive strength of Glass Fiber Reinforced-Epoxy (GFRP) woven fabric laminate is analysed. The experiments are done for four different feed rates and four spindle speeds by using a carbide drill. Thirty-two composite specimens are prepared based on the ASTM standards. The specimens are properly machined and fixed with aluminum end tab for load transfer. Strain gauges are fixed at the vicinity of hole to measure the strain. The stress concentrations caused by the presence of hole and compressive failure strength of notched laminate are arrived at theoretically and compared with the experimental values.

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